Power amplifier circuits are commonly used in a variety of applications for a number of purposes, including to apply gain to a signal to generate an amplified output signal. In some applications, the power amplifier has a single-ended output, such that a single output signal is generated. In other applications, the power amplifier has a double-ended output, such that differential (e.g., complementary) output signals are generated. In many cases, the power amplifier is driven by a voltage supply generated by a voltage supply circuit.
In many conventional applications, the voltage supply circuit seeks to maintain a constant supply voltage to the power amplifier circuit. As an example, an amplitude-modulated (AM) signal can include a radiofrequency carrier signal modulated by a lower frequency signal that manifests a changing amplitude envelope. When such an AM signal is received by a conventional power amplifier application, maintaining the constant supply voltage to the power amplifier circuit can cause certain inefficiencies, such as power loss when the amplitude envelope is less than the supply voltage.